1. Field of the Invention
The present invention relates to a circuit, apparatus, and method for antenna mode steering in a mobile communication system. More particularly, the present invention relates to an antenna mode steering circuit, apparatus, and method for selecting an antenna mode based on a received signal quality in a mobile communication system.
2. Description of the Related Art
In a radio communication system of the related art, a channel quality measured in a User Equipment (UE) may be important for a radio communication performance, and recently, there is an effort for enhancing a channel quality by suppressing interference from neighbor cells using a null steering scheme for selecting an antenna mode. In a radio communication system, different radiation patterns, which may be applied to a receiving antenna of a UE, may be acquired using Circular Patch Antennas (CPAs).
FIGS. 1A to 1D schematically illustrate a radiation pattern according to an antenna mode if CPAs are used in a Multiple Input Multiple Output (MIMO) system according to the related art.
Referring FIGS. 1A to 1D, in a MIMO system, a radiation pattern corresponding to an antenna mode is designed according to orthogonality of a radiation pattern, which is acquired using CPAs, in order to reduce a correlation among diversity branches. In this case, a diversity order increases as a number of lobes included in the radiation pattern increases, so performance may be enhanced according to an increase of the diversity order. Hence, the CPAs have an enhanced performance compared with a Uniform Linear Array (ULA) in any channel environment, and may be freely implemented compared with the ULA in a channel environment where a size limitation is severe and/or highly important. A performance of the CPAs may be theoretically analyzed using an equation indicating a spatial correlation coefficient of the CPAs, so performance of CPAs, per antenna mode, may be comparatively analyzed. As the performance of CPAs per antenna mode may be comparatively analyzed, a trade-off in a relationship between a spatial diversity and a pattern diversity may be calculated.
In a communication system of the related art, if CPAs are applied to an antenna array, a theoretical channel capacity, according to an antenna mode, may be analyzed. In further detail, an antenna array that is used has merit in any channel environment in view of the performance and the implementation as compared with the ULA that may be used. However, the merit of the antenna mode may be determined without considering a channel quality that is limited even in a case where the antenna array that is used has merit in view of a performance compared with a case where the ULA is used. If the CPAs are used, a beam pattern formed by an antenna has an orthogonal characteristic as shown in FIGS. 1A to 1D. In this case, dynamically changing the patterns may be limited according to a channel quality in view of the pattern diversity.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.